Letoff for looms

ABSTRACT

A constant warp tension letoff features an improved power path between the input shaft and letoff shaft which allows a considerable lessening of the force and tension which the transmission belt must exert on the variable cone pulleys of the letoff. A double-lead worm and gear at the letoff shaft reduces the torque which must be transmitted through the belt and cone pulley transmission. An improved weight lever mounting eliminates twisting of the weight lever which tends to cause binding. Excessive meshing of the lower worm and gear caused by heavy belt tension is eliminated.

United States Patent [72] Inventors Felix E. Hooper; 2,786,491 3/1957Hunt 139/110 Carlos Lee Owens, both of Greenville, S.C. 3,087,516 4/1963Parks 139/110 [21] Appl. No. 5,720 3,156,267 11/1964 Hooper 139/110 [22]Filed Jan. 26, 1970 3,255,784 6/1966 Rothfuss et a1. 139/110 [45]Patented Dec. 28, 1971 3,320,979 5/1967 Owens .I. 139/1 10 [73] Ass'gneegouthegnghchmery Company Primary Examiner-James Kee Chi reel"Attorney-B. P. Fishburne,Jr.

[54] LETQFF 5 4 21 ABSTRACT: A constant warp tension letoff features animschlms rawmg proved power path between the input shaft and letoffshaft [52] [1.8. CI 139/110 which allows a considerable lessening of theforce and tension [51] Int.Cl... D03d 49/06 which the transmission beltmust exert on the variable cone [50] Field of Search 139/1 10, pulleysof the letoff. A double-lead worm and gear at the letoff 109 shaftreduces the torque which must be transmitted through the belt and conepulley transmission. An improved weight [56] References Cited levermounting eliminates twisting of the weight lever which UNITED STATESPATENTS tends to cause binding. Excessive meshing of the lower worm2,755,824 7/1956 Hunt 139/1 10 and gear Caused by heavy tension is2,775,263 12/1956 Rush 139/110 34 1 1 I 6% 1 1 (7/ K 2 i O} d5 .1 79 5:1), I l u e1 1 l 7 78 29 v 1% 4i 1 a 4 ATE-P ,1 o e 7 58 TH 43 44 O l\ 745 \5 ao 39 41 47 a V J 42 Q PATtNTEnoiczmsn 31630.239

" sum 1 or 3 INVENTORS FELIX E. HOOPER CARLOS LEE OWENS ATTORNEYPATENTEUnc28t9n ajsaozas SHEET 2 OF 3 INVENTORS FELIX E. HOOPER CARLOSLEE (MENS BY KMW ATTORNEY PATENTED time 1971 sum 3 or 3 4 -333 6! [I C IRNVENTORS FELIX E. HOOPER CARLOS LEE OWENS ATTORNEY LETOFF FOR LOOMSBACKGROUND OF THE INVENTION The well-known Hunt letoff substantially inthe forms disclosed by U.S. Pat. Nos. 2,786,491 and 3,255,784 has becomethe standard of the weaving industry around the world, and more than140,000 of these Hunt letoffs are in use. Despite their wide acceptanceand success, like all mechanisms the Hunt letoff has certaindeficiencies which have come to light after long periods of operation.Among these deficiencies or defects is the tendency for the lower conepulley and worm shaft to deflect upwardly under the relatively heavytension force transmitted to this shaft by the belt which interconnectsthe upper and lower cone pulleys. In the existing letoff, the

bearings for this lower shaft are rather widely separated with the lowercone pulley and worm disposed intermediate the bearings. Consequently,upward deflection of the lower shaft under belt tension tends to causeexcessive meshing of the worm and worm gear leading to the letoff shaft,the worm being in engagement with the bottom of the worm gear. This, inturn, causes friction and wear and over a long period of time restrictsthe efiiciency of operation of the entire letoff.

Another deficiency of the existing letoff resides in the pivot mountingof the weight lever, which lever sometimes has a tendency to bind on itspivot because of twisting.

With the above in mind, his the objective of the present invention toovercome and eliminate the deficiencies of the existing Hunt letoff andto improve the reliability, efi'rciency of operation, and the durabilityof the mechanism which has already proven to be highly satisfactory. Inso doing, a letoff is provided in which constant and positive warptension and control is maintained from full to empty beam, with addedversatility for the widest range of fabrics.

Structurally, the improved letoff features a bottom cone pulley shaftwhich is separated from the worm shaft and the latter is moved overheadwith respect to the letoff shaft and is interconnected with the bottompulley shaft through a chain and sprocket drive. The two shafts arerelatively short and their bearings are relatively close together andsupport the two shafts independently and rigidly. Belt tension effectingthe bottom pulley shaft can have no effect whatsoever on theintermeshing of the worm .and gear and a consistent proper mesh can bemaintained under all conditions of loading, the use of a double-leadworm and worm gear lessens the torque which must be transmitted andconsequently relieves pressure on the belt transmission and actuallyreduces the force transmitted through the belt by as much as 3050percentin comparison to the existing mechanism. An improved bearing support forthe weight lever wherein the latter is pivoted on both sides of theletoff frame fully eliminates twisting and binding. Other features andadvantages of the invention will be apparent to those skilled in the artduring the course of the following description.

BRIEF DESCRIPTION OF DRAWING FIGURES FIG. 1 is a fragmentary sideelevation of a loom equipped with a letoff embodying the invention.

FIG. 2 is a view of the letoff along the axes of its pulley shafts, withparts in section.

FIG. 3 is a vertical section taken on line 3-3 of FIG. 1.

FIG. 4 is a fragmentary horizontal section taken on line 4- 4 of FIG. 1.

DETAILED DESCRIPTION Referring to the drawings in detail wherein likenumerals designate like parts, the numeral designates one side frame ofa weaving loom carrying a sturdybearing bracket 11 upon which the arbor12 of the usual beam 13 is joumaled. The opposite end of the beam uponwhich the warps are wound is similarly supported on the other frame sideof the loom.

The loom embodies a whip roll 14 over which the warps 15 pass undertension as they are gradually unwound from the beam during loomoperation. The whip roll is cradled on mounting arms 16 at the oppositesides of the loom, carried by shafts l7, rockably mounted on brackets 18rigid with the loom frame sides. Whip roll levers 19 are adjustablyrigidly secured to the rockable shafts 17 in a well-known manner. Thearms 16 and levers 19 are swingable vertically as a unit on the axes ofshafts 17. The forward ends of the levers 19 connect with the letoffproper in a manner to be fully described.

The letoff proper comprises a rigid frame or plate 20 in the form of acasting upon which the principal components of the letoff are mounted.The frame 20 has an opening 21 receiving a hub portion 22 of a letoffshaft bearing and mounting bracket 23 having extensions 24 bolted to theloom frame side 10 at 25. The frame 20 is rigidly and adjustably mountedon the bracket 23 and supported bodily thereon substantially as shownand described in prior US. Pat. Nos. 2,786,491 and 3,255,784.

An input shaft 26 for the letoff near its top is supported in a bearingelement 27 on the letoff frame 20 with its axis parallel to that of thebeam arbor 12, FIG. 2. The input shaft 26 has an input sprocket gear 28driven by a sprocket chain 29, in turn driven by the loom cam shaft, notshown. As shown in FIG. 2, the chain 29 is disposed between the letoffframe 20 and the adjacent loom frame side 10. On the opposite side ofthe letoff frame 20, the shaft 26 carries an input worm 30 meshing withan overhead worm gear 31 on the top cone pulley shaft 32, joumaledwithin bearings 33 and 34 carried integrally on the frame 20. This shaft32 is perpendicular to the input shaft 26 and parallel to the loom frameside 10. At one end, it carries a hand wheel 35 and at theopposite end,a manual coupling means 36 substantially as shown in US. Pat. No.2,786,49l. These details are unimportant to a full understanding of thepresent improvements.

The shaft 32 carries an upper cone pulley which embodies an axiallymovable cone disc 37 engaged by an endless transmission belt 38. Abottom cone pulley shaft 39 parallel to the shaft 32 is joumaled inbearings 40 and 41 integral with the frame 20 near its lower end. Alower cone pulley including an axially adjustable cone disc 42 ismounted on the shaft 39 and engaged by the belt 38 and it will be notedthat the two adjustable discs 37 and 42 of the pulleys are in opposedrelationship. The shaft 39 is a relatively short shaft andthe bearings41 and 40 are rather closely spaced, rendering the shaft quite rigidunder the tension force transmitted through the belt 38.

Somewhat above the shaft 39 and parallel thereto and extending beyondone end thereof is another short horizontal shaft 43 having a worm 44thereon and being joumaled in sturdy bearings 45 mounted on the frame20. The overlapping ends of the two shafts 43 and 39 carries sprocketgears 46 and 47 in vertical alignment and engaged by a short sprocketchain 48 lying outwardly of the adjacent bearing 45 and between thisbearing and the belt 38.

The worm 44 meshes with and drives a worm gear 49 on a letoff shaft 50joumaled upon the bracket 23, the latter having bearings 51 for the endsof the letoff shaft. A clutch or coupling means 52 is provided on theletoff shaft assembly for the purpose described in US. Pat. No.2,786,491 but this forms no important part of the present invention andis conventional. An oil reservoir 53 within which the gear 49 operatesis suitably secured to an extension of the frame 20.

Inwardly of the loom frame side 10, a spur gear 54 is secured to theletoff shaft 50 directly driving a larger gear 55 on the beam 13 andthus controlling the driving or turning of the beam to let off the warpsthereon. It may be emphasized at this point that the provision of thetwo short shafts 39 and 43 with the interconnecting sprocket chain means48 is a significant improvement or feature. The tension force throughthe belt 38 will cause little, if any, bending of the shaft 39, and dueto the separation of the shaft 39 and 43, the tension force through thebelt can have no effect on the shaft 43. In the prior art, as previouslymentioned, a single-bottom pulley shaft was employed and the wormdriving the letoff shaft was located at the bottom of the worm gearonthe letoff shaft. The longer single shaft sometimes tended to bowupwardly under belt tension forces and wedge the worm too tightly intomesh with the worm gear, resulting in damage to the equipment.

The control components of the letoff include an improved weight lever 56carrying weight 57 at its free end and having a main pivot shaft or pin58 adjacent its other end. As shown in FIGS. 2 and 4, the pivot pin 58is supported in a bearing part 59 on the frame and the weight lever hasa U-shaped extremity 60 near its pivoted end having separated bearings61 which receive the pin 58 and straddle the intermediate bearing part59. This wide bearing support on the frame 20 in conjunction with anoffset 62 in the weight lever stabilizes the weight lever andsubstantially eliminates twisting thereof and binding of the weightlever pivot which has been troublesome in the past.

The weight lever is counterbalanced by a generally vertical tension link63 pivotally connected at its top to the lever 19 as indicated at 64.The lower end of tension link 63 is similarly connected to a cross pivotpin 65, HO. 4, which engages both arms of the U-shaped extremity 60. Anupper control lever 66 is pivoted at 67 to a portion of the frame 20 andhas an upper yoke 68 which engages a thrust collar 69 associated withthe shiftable cone disc 37 to move the same axially. The control lever66 has a lower extension 70 connected to an adjustable link 71 near theelevation of the weight lever 56 and the link 71 is pivotally connectedat 72 to the upper arm 73 of a second control lever 74 having a loweryoke 75 engaging a thrust collar 76 on the shiftable cone disc 42 of thelower variable cone pulley. The control lever 74 is pivotally mounted ona pin 77 also anchored to the letoff frame 20. Another shortsubstantially vertical link 78 interconnects a horizontal extension 79of control lever 66 with the pivot pin 65 as shown clearly in FIGS. 1and 3. The link 78 lies between the sides of U-shaped extremity 60 asshown in FIG. 4.

It may readily be seen that the effect of the weights 57 on the weightlever 56 pivoted at 58 is counteracted by the tension link 63, lever 19and whip roll 14 pivoted at 17. As the diameter of the warp beam 13decreases, a constant warp tension is maintained by the automaticoperation of the letoff including the operation of the twointerconnected control levers 66 and 74 which are tied into the weightlever 66 and tension link 63 through the common pivot pin 65. Thus, thediameters of the two cone pulleys will adjust or compensateautomatically to maintain a constant tension on the warps 15 at alltimes. This mode of operation is disclosed fully in US. Pat.

No. 2,786,491 and need not be described further herein. As alreadystated, the present invention is concerned primarily with structuralfeatures of theletoff which improve its effciency, durability andversatility.

It is to be understood that the form of the invention herewith shown anddescribed is to be taken as a preferred example of the same, and thatvarious changes in the shape, size and arrangement of parts may beresorted to, without departing from the spirit of the invention or scopeof the subjoined claims.

1. A letoff for a loom comprising a support frame attachable fixedly toa loom, an upper variable diameter pulley shaft journaled on saidsupport frame on a fixed rotational axis, input drive means for saidupper variable diameter pulley shaft operating while the loom is inoperation, a lower variable diameter pulley shaft journaled on saidsupport frame on a fixed rotational axis substantially parallel to therotational axis of said upper pulley shaft and substantially in a commonvertical plane therewith, variable diameter pulley transmission meansincluding a transmission belt interconnecting said upper and lowershafts, yielding control linkage means for said transmission meanshaving a connection with the whip roll of the loom, a letoff shaftjournaled on the support frame on a fixed rotational axis near theelevation of said lower pulley shaft and spaced from one end of thelower pulley shaft, the rotational axes of the lower pulley shaft andsaid letoff shaft being substantially at right angles, said letofi shaftadapted to drive a warp beam ontheloom through gearing, a worm gear onsaid letoff shaft adapted to be driven, a drive shaft journaled uponsaid support frame above and parallel to the axis of the lower pulleyshaft and disposed on a fixed rotational axis substantially at rightangles to the axis of the letoff shaft spaced thereabove, a worm on saiddrive shaft in fixed meshed relation with the worm gear of the letoffshaft, adjacent end portions of said lower pulley shaft and drive shaftoverlapping, and additional gearing drivingly interconnecting saidoverlapping end portions.

2. The structure of claim 1, and said additional gearing comprising apair of sprocket gears on said overlapping end portions, and a sprocketchain engaging said sprocket gears.

37 The structure of claim 1, and a pair of bearings for said drive shafton said support frame spaced closely on opposite sides of said worm,both said bearings disposed on one side of said additional gearing.

1. A letoff for a loom comprising a support frame attachable fixedly toa loom, an upper variable diameter pulley shaft journaled on saidsupport frame on a fixed rotational axis, input drive means for saidupper variable diameter pulley shaft operating while the loom is inoperation, a lower variable diameter pulley shaft journaled on saidsupport frame on a fixed rotational axis substantially parallel to therotational axis of said upper pulley shaft and substantially in a commonvertical plane therewith, variable diameter pulley transmission meansincluding a transmission belt interconnecting said upper and lowershafts, yielding control linkage means for said transmission meanshaving a connection with the whip roll of the loom, a letoff shaftjournaled on the support frame on a fixed rotational axis near theelevation of said lower pulley shaft and spaced from one end of thelower pulley shaft, the rotational axes of the lower pulley shaft andsaid letoff shaft being substantially at right angles, said letoff shaftadapted to drive a warp beam on the loom through gearing, a worm gear onsaid letoff shaft adapted to be driven, a drive shaft journaled uponsaid support frame above and parallel to the axis of the lower pulleyshaft and disposed on a fixed rotational axis substantially at rightangles to the axis of the letoff shaft spaced thereabove, a worm on saiddrive shaft in fixed meshed relation with the worm gear of the letoffshaft, adjacent end portions of said lower pulley shaft and drive shaftoverlapping, and additional gearing drivingly interconnecting saidoverlapping end portions.
 2. The structure of claim 1, and saidadditional gearing comprising a pair of sprocket gears on saidoverlapping end portions, and a sprocket chain engaging said sprocketgears.
 3. The structure of claim 1, and a pair of bearings for saiddrive shaft on said support frame spaced closely on opposite sides ofsaid worm, both said bearings disposed on one side of said additionalgearing.